What differentiated instruction works in your classroom?

While true that I am not in the classroom as teacher anymore, I was always a fan of having students pick a topic to research within a defined assignment. Students were then required to present their findings to their class--even though I taught science, I required students to create some form of visual display for a number of their presentations--visual could be a physical model, poster, computer presentation. After the in class presentations, I would often hold the class responsible for what their peers had taught. I often learned from my students too.